import 'dart:math';

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
        // This makes the visual density adapt to the platform that you run
        // the app on. For desktop platforms, the controls will be smaller and
        // closer together (more dense) than on mobile platforms.
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 12;
  List<String> _list = List.generate(26, (index) {
    var firstChar = "A".codeUnits.first;
    return String.fromCharCode(firstChar + index);
  }); //["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "b", "b", "b", "b", "b", "b", "b", "b", "b", "b", "b", "b", "b"];
  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
        appBar: AppBar(
          // Here we take the value from the MyHomePage object that was created by
          // the App.build method, and use it to set our appbar title.
          title: Text(widget.title),
        ),
        body: ListView.builder(
            itemCount: _list.length,
            itemBuilder: (ctx, index) {
              var title = _list[index];
             return Dismissible(
                 key: Key(title),
                 onDismissed: (_) {
                   _list.removeAt(index);
                 },
                 movementDuration: Duration(microseconds: 250),
                 child: ListItem(
                   title: _list[index],
                 ));
//               return GestureDetector(
//                   onLongPress: () {
//                     setState(() {
//                       _list.removeAt(index);
//                     });
//                   },
//                   child: ListItem(
//                     title: _list[index]
//                     ,
//                   )
//               );
            }));
  }
}

class ListItem extends StatefulWidget {
  final String _title;

  ListItem({String title}) : this._title = title;

  @override
  _ListItemState createState() => _ListItemState();
}

class _ListItemState extends State<ListItem> {
  final Color _color = Color.fromARGB(
      255, Random().nextInt(255), Random().nextInt(255), Random().nextInt(255));

  @override
  Widget build(BuildContext context) {
    return Container(
      padding: EdgeInsets.only(left: 20, top: 10, bottom: 10),
      width: double.infinity,
      color: _color,
      child: Text(widget._title),
    );
  }
}